In addition to my last comment on an aftermarket alternative, I have located a few images of the Stop Bolts, the Allen or button version and the 1/2" wrench hex bolt version. There has been discussion of a 3rd style but I haven't found any pictures of it yet.
Two points I wish to make with this comment. 1.) You can switch out an incorrect stop bolt if it is the wrong one (though you MUST disassemble the cylinder to secure the lower piston beyond the stop bolt if you switch it) and
2.) A person MIGHT find a cylinder with the correct 2227161 casting that does not have a stop bolt (later versions) and machine the area and drill a shallow hole, thread the hole and insert a shortened version of the stop bolt in the correct location, thus SIMULATING a stop bolt in a newer casting.